JP2860397B2 - Screw type steam compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw type vapor compressor used in a refrigeration cycle or a heat pump cycle. In a refrigeration cycle or a heat pump cycle, a compressor used in the cycle sucks the working medium gas in a state of saturated steam or superheated steam, and compresses and discharges it to a high-temperature, high-pressure superheated steam state.

[0002] Such a vapor compressor includes a reciprocating compressor and a rotary compressor. In addition, a relatively high condensing pressure or a low evaporating pressure requires operation at a high pressure ratio. In this case, a screw compressor is used as a suitable compressor. The screw compressor has the advantages that it can process a large volume of gas at high speed, has little wear, has a higher pressure ratio with a rotor oil seal, and is less susceptible to liquid return.

[0003]

2. Description of the Related Art Conventionally used screw compressors include a single-screw screw compressor and a twin-screw screw compressor. Both of them have a small gas suction volume with respect to the total volume of the compressor and have a single-shaft screw compressor. In a compressor, a screw rotor is a single-shaft type, but in addition to this, two gate rotors are required, which complicates the structure. In addition, a twin-screw screw compressor requires a pair of male and female rotors, which complicates the structure. .

[0004]

On the other hand, refrigerants used in compressors include chlorofluorocarbons, whose use has been restricted in recent years as a factor in global warming due to the need to preserve the global environment. Have been. Therefore, it is desirable to use water and other substances that do not affect the global environment in refrigerators and heat pumps.However, water reduces volumetric efficiency compared to CFC-based systems, and increases the size of the compressor. In addition, since the discharge temperature is high, in the conventional screw type compressor having a small suction volume with respect to the total volume of the compressor,
It is economically difficult to use water as a working medium.
Further, since the discharge temperature of water is higher than that of a chlorofluorocarbon-based refrigerant, the conventional screw compressor cannot be used as it is from this point. The present invention has been made in view of the above circumstances, and has a simpler structure than a conventional screw compressor, and has a drastically increased suction volume with respect to the entire volume of the compressor. It is an object of the present invention to provide a screw-type steam compressor that can prevent overheating of the discharge gas.

[0005]

In response to this object, a screw-type steam compressor according to the present invention comprises a horizontally disposed cylinder and a rotor rotating in the cylinder.
And a liquid sealing medium accommodated in the cylinder, wherein the rotor has a rotor shaft and a screw blade attached to the rotor shaft, and the rotor shaft has a working medium vapor suction side. The diameter of the screw blade is gradually increasing toward the discharge side and is in contact with the sealing medium, the pitch of the screw blade is gradually reduced from the suction side of the vapor toward the discharge side, and the rotation axis of the rotor is the cylinder. And a liquid seal by the seal medium is formed between the lower part of the rotor shaft and the cylinder, and a liquid seal above the liquid surface of the seal medium is formed .
Only a working space is formed .

[0006]

In the screw type steam compressor according to the present invention, the compression space is constituted by only a cylinder and one rotor, and the compression space is defined as a space surrounded by a cylinder wall, a spiral screw blade and a rotor shaft, and a liquid surface of a sealing medium. It is formed. The rotor is composed of a helical screw blade and a conical rotor shaft that advance while narrowing the pitch from the suction section to the discharge section. The working medium gas sucked in with the rotation of the compressor is continuously compressed and discharged from the discharge port. Since only a cylinder and one rotor are used as components, the structure is simpler than that of a conventional screw compressor, and the suction volume with respect to the entire volume of the compressor is dramatically increased due to the large compression space. In addition, it becomes a state of two-phase compression that compresses steam and working medium at the same time,
Overheating of the discharge gas after compression can be prevented.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings showing one embodiment.

In FIGS. 1, 2 and 3, reference numeral 1 denotes a vapor compressor. The steam compressor 1 has a cylinder 2. The cylinder 2 has an internal space 3 and a central axis 4 of the internal space 3.
The cylinder 2 is arranged so that is positioned horizontally. The internal space 3 has a suction port 5 and a discharge port 6 at both ends.
Are in communication. In the internal space 3 of the cylinder 2, a rotor 7 is disposed so as to be able to rotate in an airtight manner. Further, a sealing medium 8 such as water is accommodated in the internal space 3.
This sealing medium is made of the same material as the working medium of the heat cycle in which the steam compressor 1 is included. Therefore, if the working medium of the heat cycle is water or a mixture of water and an alcohol such as ethanol, the sealing medium is also made of water. Alternatively, it is a mixture of water and an alcohol such as ethanol.

The rotor 7 is composed of a rotor shaft 11 and a screw blade 12. The rotor shaft 11 has a conical shape with a small diameter on the suction port side and a gradually increasing diameter on the discharge port side, and the rotation center axis of the rotor shaft 11 coincides with the center axis 4 of the internal space 3 of the cylinder 2. Are arranged as follows. The screw blade 12 is spirally mounted on the rotor shaft 11, and has an outer shape substantially equal to the inner diameter of the internal space 3 of the cylinder 2. Therefore, when the rotor 7 rotates in the internal space 3, the outer peripheral edge of the screw blade 12 slides on the wall surface of the internal space 3 in an airtight manner. The pitch of the screw blade 12 gradually decreases from the suction side to the discharge side. The screw shaft 11 always comes into contact with the seal medium 8 to form a liquid shaft seal. In order to secure the contact between the rotor shaft 11 and the liquid seal medium 8, the diameter of the rotor shaft 11 changes. In addition, the capacity of the sealing medium 8 is adjusted. The liquid sealing medium 8 communicates with a communication groove 15 formed below the internal space 3 of the cylinder 2. The compression space 13 is a space surrounded by the wall of the cylinder 2, the screw blade 12, the rotor shaft 11 and the liquid surface 10 of the liquid sealing medium 8, and such a compression space 13 is formed between adjacent screw blades 12 at every pitch. A plurality is formed from the suction port 5 side to the discharge port 6 side. These plural compression spaces 1
3 are independent of the security structure, and do not communicate with the adjacent compression space. However, each compression space 1
3 is the pitch of the screw blade 12 and the rotor shaft 1
The volume differs according to the change in the diameter of the suction port 5.
The volume of the compression space 13a on the side of the discharge port 6 is the largest, and the volume of the compression space 13e on the side of the discharge port 6 is the smallest. The rotor 7 is driven to rotate by a motor 14. As each compression space 13 moves from the suction port 5 side to the discharge port 6 side in the central axis direction, the volume changes from the largest one to the smallest one.

[0010] In the screw-type steam compressor constructed as described above, the steam is compressed as follows. Steam guided from an evaporator (FIG. 4) such as a heat pump is sucked from the suction port 5 and enters the compression space 13. Motor 14
Of the rotor 7 and the screw blade 1
Due to the rotation of 2, the volume of the compression space 13 decreases as the compression space 13 moves to the discharge port 6 side, and accordingly, the vapor of the working medium in the compression space 13 is compressed. Finally, the liquid is discharged from the discharge port 6. In each of the compression spaces 13, the liquid sealing medium is also subjected to the compressing action at the same time.
Is connected to the liquid part in the lower part of the preceding compression space, and the liquid level of each compressor is pushed down according to the pressure, but the liquid sealing medium escapes until it equilibrates with the liquid part of the previous compression space, so damage to the equipment Does not occur. During the compression, the vapor in the compression space 13 pushes down the liquid surface of the liquid sealing medium below the compression space 13 due to the pressure increase, but the liquid surface moves away from the shaft because the rotor shaft has a conical shape. Without
Therefore, the security of the compressed space is maintained.

[0011]

The structure of the screw-type steam compressor is simple because there is only one rotor.
Since the sealing is performed at the liquid surface of the sealing medium instead of the conventional sealing between rotors, high processing accuracy for maintaining the secrecy of the compression space is not required. In addition, since liquid is used for sealing, gas-liquid two-phase compression occurs in the compression space, and the compressed gas of the working medium is cooled by the liquid sealing medium, so that the temperature of the discharged gas is not overheated. Yes. Moreover, in the compression space on the suction side,
Since the rotor shaft diameter is small and the blade pitch is large, a large space can be secured, and the amount of suction gas can be increased, which makes the overall compressor more compact than conventional screw compressors. The suction volume to volume increases. In addition, since water can be used as a working medium, it is safe and pollution-free.

Further, from this, even when it is necessary to increase the distance between the compressor and the heat exchanger, for example, the amount of working medium to be filled is not limited, so that the degree of freedom of the system layout is increased. Can be. As described above, according to the present invention, the screw type which has a simple structure, can greatly increase the suction volume with respect to the entire volume of the compressor, and can prevent overheating of the discharge gas after compression by gas-liquid two-phase compression. A steam compressor can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view of a screw type steam compressor.

FIG. 2 is an explanatory view of a longitudinal section of a screw type steam compressor.

FIG. 3 is an explanatory sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a diagram illustrating the configuration of a heat pump cycle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam compressor 2 Cylinder 3 Internal space 4 Central axis 5 Suction port 6 Discharge port 7 Rotor 8 Working medium 10 Liquid surface 11 Rotor shaft 12 Screw blade 13 Compression space 14 Motor 15 Communication groove

Claims (2)

(57) [Claims] 1. A system comprising a horizontally disposed cylinder, a rotor rotating in the cylinder, and a liquid sealing medium contained in the cylinder, wherein the rotor is attached to the rotor shaft and the rotor shaft. The rotor shaft has a diameter gradually increasing from the suction side of the working medium vapor toward the discharge side,
And in contact with the sealing medium, the screw blade has a gradually decreasing pitch from the vapor suction side to the discharge side, and the rotation axis of the rotor coincides with the center line in the cylinder, and A screw type vapor compression, wherein a liquid seal by the seal medium is formed between a lower part of a rotor shaft and the cylinder, and an operation space is formed only above a liquid surface of the seal medium. Machine. 2. The screw-type steam compressor according to claim 1, wherein the working medium and the sealing medium are water or a mixture of water and an alcohol such as ethanol.